Blower wheel construction

ABSTRACT

This invention relates to the attachment of blower wheel blades to support discs with interlocking notches secured by the wedging action of an internal spring retaining ring acting between the disc and the sloping surface of an inner notch in the blades.

United States Patent 1 1 1111 3,816,023 Shaver June 11, 1974 [5 BLOWER WHEEL CONSTRUCTION 3,385,5ll 5/1968 Wentling 4l6/l78 I 3,635,588 l/l972 Lester et al.... 4l6/l87 [75] Inventor- Lyle Shave" Blue SPmES1MO' 3,641,644 2/1972 Cunniffet al 416/187 [73] Assignee: Allis-Chalmers Corporation,

Mllwaukee Primary Examiner-Everette A. Powell, Jr. 22 Filed; Oct 2 1972 sslstant xammer- UlS asarego a A E Lo L C l [2 1 App o 9 9 Attorney, Agent, or Firml(enneth C. McKivett [52] US. Cl. 416/178, 416/187 ABSTRACT l' l f Z 3 g This invention relates to the attachment of blower 41 6 6 wheel blades to support discs with interlocking notches secured by the-wedging action of an internal spring retaining ring acting between the disc and the [56] UNITE E S ?Z; ES SZqFENTS sloping surface of an inner notch in the blades.

2,392,l l3 H1946 Anderson 416/184 9 Clains, 9 Drawing Figures mnmznm 11 an 3.8163323 SHEET 1 BF 3 SEPARATOR DUCT BLOWER WHEEL CONSTRUCTION This invention is concerned with providing a blower wheel structure which is simple and rigid in construc tion, easy to assemble, requires a minimum amount of tooling and can be built in any desired length at a minimum cost.

In the past, blades in blowers, have been attached to support discs by numerous methods including riveting, welding, and deforming either the discs or the blades to lock them together. Riveting requires considerable assembly time and is difficult to automate. Welding often causes warping. Various methods of deforming the discs or the blades is often complicated and requires considerable investment in tooling and past methods required that intermediate discs and end discs be attached in a different manner.

In the present invention, all blades are attached to support discs in an identical manner. There is no welding or riveting. Only one fastening device is required at each support disc to attach all blades. Assembly of blades requires a minimum of time and only simple tools are required. Use of centrifugal force is made to retain the blades in position by pulling them tightly against the outer end of a closed slot in support discs and centrifugal force also aids the expansion and wedging action of an internal retaining ring against the inner end of the blade.

An object of this invention is to provide a transverse fan requiring a minimum number of different parts,

A further object of this invention is to provide a trasnsverse fan wherein individual blades thereof may be readily replaced in the field in case of damage.

A further object of this invention is to provide a transverse fan which is readily balanced.

Other features and advantages will appear in the following description and appended claims, reference being bad to the accompanying drawings forming a part of this specification wherein:

FIG. 1 is a side elevation of a blower in a combine harvester with parts of the combine removed for clarity of illustration;

FIG. 2 is a longitudinal partial section taken through two adjacent support discs on line II-II of FIG. 1;

FIG. 3 is a partial section view taken along line III- ---III of FIG. 2;

FIG. 4 is a partial section view taken along line lV-IV of FIG. 3;

FIG. 5 is a partial section view similar to FIG. 2 illustrating an alternate type of construction;

FIG. 6 is a partial section view taken along line VI-VI of FIG. 5;

FIG. 7 is an illustration similar to FIG. 2 showing an alternative construction;

FIG. 8 is an illustration similar to FIG. 2 showing an alternative construction using a pair of stub shafts in place of a single shaft; and

FIG. 9 is an illustration similar to FIG. 2 showing an alternative construction adapted for use as a centrifugual fan.

Referring to FIG. 1 of the drawings, a blower rotor 10 for a transverse flow fan combination 11 positioned for operation in a combine harvester isshown. This fan is provided with dual outlets 12 and 13 providing a supply of air to the separator and cleaner ducts 14 and 16, respectively, of the harvester. Ducts l4 and 16 are provided with dampers l7 and 18, respectively, for regulating the flow of air through such ducts. This fan is also provided with an air receiving opening 19 extending the entire length of the fan. An adjustable vane 21 is mounted on the harvester and can be adjusted to control the volume of air entering opening 19.

Fan 11 includes a central shaft 22 which is driven by power means (not shown) on the harvester. I-Iub members 23 may be attached to shaft 22 by various means such as set screws, keys, roll pins or bonding (locktite).

Discs 24 are attached to hub members 23 as be welding flanges of the discs 24 to hubs 23.

Rotor 10 includes a plurality of circumferentially disposed blades 27. Normally the blades 27 are curved with the projection of the leading or outer edge thereof making an angle of attack of 20 to 40 with a tangent to the wheel circumference as shown in FIG. 3, and the inner blade surface 28 extends approximately radially from the longitudinal center line of shaft 22.

Since the length of a transverse fan is functionally unlimited, several intermediate support discs 24 may be required to support and counteract centrifugal force acting on blades 27.

Details of the rotor 10 are shown in FIGS. 2 and 3 and referring to such FIGS., the support discs 24 have a plurality of closed slots 29 equally spaced and positioned near the periphery of the disc. The shape of these slots 29 includes a curved surface 31 conforming to the blade shape to provide support and an outer surface 32 to intercept the outer ends of blades 27 to prevent outward radial movement thereof. The remaining slot surfaces 33 are shaped for convenience of manufacture and also to permit free passage when blades 27 are being inserted endwise into slots 29 for easy assembly.

After the blades 27 are slipped through slots 29, it is seen that each blade is provided with a series of outer notches 34 (see FIG. 2) corresponding with the number of support discs 24 being used and these outer notches 24 are transversely aligned with the support discs 24. These relatively shallow notches 34 have an outer width 36 slightly greater than the disc thickness to allow interlocking. The sides 37 of these notches may also be tapered to provide a wedging action when forced over the disc. In radial alignment with notch 34 is an inner notch 38 provided with a sloping surface 39 to provide a radial outward force to insure interlocking of notches 34 with discs 14.

To lock blades 27 to the discs 24, a spring retaining ring 42 is compressed and installed in notches 38 adjacent to discs 24. The retaining rings 42 are installed on opposite sides of adjacent discs 24 to counteract the axial force exerted on the blade by the wedging action of the rings acting on sloping surfaces 39. During the operation of blower 10, centrifugal force pulls the blades 27 into tight contact with discs 24 at the outer notches 34 and also causes the retaining rings 42 to expand tighter into the inner notches 38 thus affecting a relatively rigid connection between blades 27 and discs 24.

To prevent rotation of retaining rings 42 relative to discs 24 and blades 27 and to compensate for the imbalance caused by gap 43 in the rngs 42, a tab 44 (FIG. 3) may be formed on one end of the rings 42. The length of tab 44 is approximately equal to the width of gap 43. When installed tabs 44 (FIG. 4) protrude through slots 29 in discs 24 thus preventing rotation of the ring and compensating for the aforementioned imbalance. Adjacent rings 42 may also be installed with their gaps on opposite sides of their discs to maintain balance. FIGS. 5 and 6 illustrate an alternate construction. The axial force exerted on blades 27a by the retaining rings 42 is counteracted by a tab 46 formed in the blade adjacent to notch 38. When blade 27a is in proper position, this tab 46 locks against the opposite side of discs 24 forming a rigid attachment in cooperation with the retaining ring 42.

FIG. 7 shows another alternative design of more rigid construction. In this design, a second retaining ring 42 is used on the opposite side of the support discs 24. This combination increases the rigidity of the bladedisc joint. Also a flange 47 is added to the outer periphery of disc 24 and a conical stiffener 48 is spot welded between the disc and hub for additional strength. Although a transverse flow rotor is illustrated in the drawings, the shown construction is also applicable to centrifugal blowers. By removing a central portion of one or more of the end discs, air inlets would be provided.

Although the embodiments of this invention so far have been shown as having an inner and outer blade notch which provides maximum rigidity of blade to disc connection, either notch alone is sufficient to interlock the blade with the disc. By using an appropriate fixture during assembly to axially locate the blades, the retaining rings 42 can be installed in the inner notches to locate and secure the blades to the discs. Thus, the necessity for the outer notch is eliminated as is shown in FIG. 8.

In FIG. 8 a modified embodiment of this invention is shown. In place of having discs 24b attached to a central shaft, two stub shafts 49 and 51 are provided which are keyed to hubs 52 and 53, respectively, for rotation therewith. Discs 24b are attached to hubs 52 and 53 as by welding. A central disc 54 is provided which is entirely supported from blades 27b for stiffening same. This type of construction, using stub shafts, is entirely satisfactory for short rotor assemblies. In fact, if a single central shaft is not required structurely, its elimination from the center of the rotor improves fan efficiency. Where structural considerations permit, the rotor can be driven and supported by attaching means (e.g. gudgeons) to the outer discs only. Retaining rings 42 positioning in notches 38b retain the blades 27b positioned on discs 24b.

FIG. 9 shows a modified construction which adapts this invention for use in a centrifugal fan. In this embodiment the blades 27c are mounted on a pair of closely spaced discs 240 which are attached to a central shaft through the medium of an intervening hub 56.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A fan rotor comprising a pair of discs longitudinally spaced apart and attached to rotatable means;

a plurality of arcuate blades supported on said discs longitudinally parallel to the axis of rotation of said rotor;

said discs being provided with a plurality of closed slots therein with each slot having an arcuate surface complementary to said blades;

said slots being of a size permitting said blades to be inserted endwise therethrough;

said blades being provided with notches spaced apart longitudinally the same as the spacing between the discs so that when said blades are slid longitudinally through said slots registry is obtained between said notches and said discs;

and radially outward acting spring means positioned adjacent said discs and contacting radially inner portions of said blades for biasing same radially outward interlocking said blades with said discs.

2. A fan rotor as recited in claim 1 and wherein said notches are provided in the outer portion of said blades.

3. A fan rotor as recited in claim 1 wherein said notches are provided in the inner portion of said blades.

4. A fan rotor as recited in claim 2 and wherein said blades are provided with inner notches in radial align- 5. A fan rotor as recited in claim 4 and wherein said spring means comprises. ring shaped springs positioned on each side of each disc and in contact therewith and positioned in said inner notches.

6. A fan rotor as recited in claim 5 and wherein said spring means includes a ring shaped spring having an opening therein, an offset portion extending at right angles thereto and into one of said slots so that said offset portion prevents rotation of said spring means relative to said disc, said offset portion being of size to counterbalance said spring means relative to said opening therein.

7. A fan rotor as recited in claim 6 and wherein said notches are tapered to provide a locking engagement between said blades and said discs.

8. A fan rotor as recited in claim 7 and wherein the distal ends of said discs are turned over at right angles thereto for stiffening said rotor.

v 9. A fan motor as recited in claim 3 wherein said spring means is received in said notches in the inner portion of said blades whereby said spring means biases said blades radially outward against the outer ends of said slots and locks said blades against movement in at least one axial direction relative to said discs. 

1. A fan rotor comprising a pair of discs longitudinally spaced apart and attached to rotatable means; a plurality of arcuate blades supported on said discs longitudinally parallel to the axis of rotation of said rotor; said discs being provided with a plurality of closed slots therein with each slot having an arcuate surface complementary to said blades; said slots being of a size permitting said blades to be inserted endwise therethrough; said blades being provided with notches spaced apart longitudinally the same as the spacing between the discs so that when said blades are slid longitudinally through said slots registry is obtained between said notches and said discs; and radially outward acting spring means positioned adjacent said discs and contacting radially inner portions of said blades for biasing same radially outward interlocking said blades with said discs.
 2. A fan rotor as recited in claim 1 and wherein said notches are provided in the outer portion of said blades.
 3. A fan rotor as recited in claim 1 wherein said notches are provided in the inner portion of said blades.
 4. A fan rotor as recited in claim 2 and wherein said blades are provided with inner notches in radial alignment with said outer notches, and said spring means being received in said inner notches for biasing said blades radially outward against a surface of said disc extending generally parallel the periphery of said disc.
 5. A fan rotor as recited in claim 4 and wherein said spring means comprises ring shaped springs positioned on each side of each disc and in contact therEwith and positioned in said inner notches.
 6. A fan rotor as recited in claim 5 and wherein said spring means includes a ring shaped spring having an opening therein, an offset portion extending at right angles thereto and into one of said slots so that said offset portion prevents rotation of said spring means relative to said disc, said offset portion being of size to counterbalance said spring means relative to said opening therein.
 7. A fan rotor as recited in claim 6 and wherein said notches are tapered to provide a locking engagement between said blades and said discs.
 8. A fan rotor as recited in claim 7 and wherein the distal ends of said discs are turned over at right angles thereto for stiffening said rotor.
 9. A fan motor as recited in claim 3 wherein said spring means is received in said notches in the inner portion of said blades whereby said spring means biases said blades radially outward against the outer ends of said slots and locks said blades against movement in at least one axial direction relative to said discs. 